Intervertebral Spacer for TLIF Implant Procedure

ABSTRACT

An intervertebral spacer is disclosed having a main body and an articulating component that is pivotally mounted within an opening of the main body. The intervertebral spacer is designed to be manufactured using an additive manufacturing process without the use of any frangible support material between a main body of the intervertebral spacer and an articulating component of the intervertebral spacer. To this end, an article of manufacture is provided in which supports are formed prior to forming intervertebral spacer. The supports are configured to support the main body and the articulating component such that they can be separately, but simultaneously manufactured using an additive manufacturing process atop the supports, without the need for any frangible support material therebetween.

This application is a divisional of co-pending application Ser. No.16/930,605, filed on Jul. 16, 2020, which claims the benefit of priorityof U.S. provisional application Ser. No. 62/881,581, filed on Aug. 1,2019, the disclosures of which are herein incorporated by reference intheir entirety.

FIELD

The device and method disclosed in this document relates tointervertebral implants or spacers for fusing vertebral bodies and, moreparticularly, to an intervertebral spacer configured and dimensioned tobe implanted transforaminally.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not admitted to be prior art by inclusion in this section.

In humans, the normal spine has seven cervical, twelve thoracic and fivelumbar segments. The bony vertebral bodies of the spine are separated byintervertebral discs, which act as joints but allow known degrees offlexion, extension, lateral bending, and axial rotation. The typicalvertebra has a thick anterior bone mass called the vertebral body, witha neural (vertebral) arch that arises from the posterior surface of thevertebral body. The central portions of adjacent vertebrae are supportedby intervertebral discs. Each neural arch combines with the posteriorsurface of the vertebral body and encloses a vertebral foramen. Thevertebral foramina of adjacent vertebrae are aligned to form a vertebralcanal, through which the spinal sac, cord and nerve rootlets pass. Theportion of the neural arch which extends posteriorly and acts to protectthe posterior side of spinal cord is known as the lamina. Projectingfrom the posterior region of the neural arch is the spinous process.

The intervertebral disc primarily serves as a mechanical cushionpermitting controlled motion between vertebral segments of the axialskeleton. A normal and healthy intervertebral disc is a unique, mixedstructure, comprised of three component tissues: the nucleus pulpous(“nucleus”), the annulus fibrosus (“annulus”), and two vertebral endplates. The two vertebral end plates are composed of thin cartilageoverlying a thin layer of hard, cortical bone which attaches to thespongy, richly vascular, cancellous bone of the vertebral body. The endplates thus act to attach adjacent vertebrae to the disc.

The spinal disc and/or vertebral bodies may be displaced or damaged dueto trauma, disease, degenerative defects, or wear over an extendedperiod of time. One result of this displacement or damage to a spinaldisc or vertebral body may be chronic back pain.

A disc herniation occurs when the annulus fibers are weakened or tornand the inner tissue of the nucleus becomes permanently bulged,distended, or extruded out of its normal, internal annulus confines.Alternatively, with disc degeneration, the nucleus loses itswater-binding ability and deflates, as though the air had been let outof a tire. Subsequently, the height of the nucleus decreases causing theannulus to buckle in areas where the laminated plies are loosely bonded.Adjacent, ancillary spinal facet joints will also be forced into anoverriding position, which may create additional back pain.

Whenever the nucleus tissue is herniated or removed by surgery, the discspace will narrow and may lose much of its normal stability. In manycases, to alleviate back pain from degenerated or herniated discs, thedisc is removed along with all or part of at least one neighboringvertebrae and an implant is introduced into the resulting space thatpromotes fusion of the remaining bony anatomy. The implant or spacer,which can be in the form of a cage, fills the space left by the removeddisc and bony anatomy and must be sufficiently strong to support thespine under a wide range of loading conditions. The spacer should alsobe configured so that it is likely to remain in place once it has beenpositioned in the spine by the surgeon. Optimally, the spacer isdesigned to promote bony ingrowth through the spacer, which a can beaccomplished by the physical structure of the spacer, as well as formingthe spacer of a biocompatible material that at least accommodates, ifnot promotes, bony tissue ingrowth.

Instrumentation and specialized tools for insertion of an intervertebralspacer is yet another design parameter to consider when designing aspacer. Spinal fusion procedures can present several challenges becauseof the small clearances around the spacer when it is being inserted intoposition. For instance, the instrumentation used may securely grip thespacer on opposing sides or surfaces. Thus, the clearance required inorder to insert such a spacer must be greater than the spacer itself inorder to accommodate the instrumentation. For this reason, distractionof the treated area typically is greater than the spacer itself.Similarly, when the gripping tools used to manipulate and insert thespacer are on the sides of the spacer, additional clearance typically isneeded in order to accommodate the added width of the insertion toolblades. Such increases in height or width of the profile of the spacerwhen coupled or in communication with instrumentation means thatadditional space is needed in order to insert the spacer. In somecircumstances, providing for this additional clearance space can bedifficult to achieve.

It is thus well known to immobilize two vertebrae relative to oneanother using an intervertebral implant made from a rigid material,forming a cage that delimits a housing that is configured to receive oneor several bone grafts and/or spongy bone chips. Some intervertebralcages or spacers are implanted through a posterior approach called“PLIF” (acronym for Posterior Lumbar Interbody Fusion), others throughan anterior approach “ALIF” (Anterior Lumbar Interbody Fusion), andstill others through a transforaminal approach or “TLIF” (TransforaminalLumbar Interbody Fusion).

FIGS. 1A-1D depict an exemplary transforaminal approach for implantingan intervertebral spacer 10. In this approach, the spacer 10 has acurved contour that facilitates its introduction into the intervertebralspace using an insertion tool T. The insertion tool T is engaged at aninterface I to an articulating or rotating element 12 of the spacer 10.The insertion tool T also includes a stabilizer component S that engagesthe end of the spacer 10 to hold the insertion tool T in a fixedrelationship to the spacer 10. Thus, as can be seen in FIG. 1A, in aninitial step, the insertion tool T is engaged to the spacer 10 with thestabilizer component S such that the spacer 10 is, in essence, a rigidextension of the insertion tool T. The spacer 10 is introduced to adesired positioning or depth between adjacent vertebral bodies using atransforaminal approach. With the spacer 10 initially positioned, thestabilizing component S is retracted, as shown in FIG. 1B, with theinterface I still engaged to the spacer 10. With the stabilizercomponent disengaged from the spacer 10, the spacer 10 is free to pivotwithin the intervertebral space as the insertion tool T is advanced intothe intervertebral space, as shown in FIGS. 1C-1D. Once impacted to thedesired position, such as adjacent the epiphyseal ring, the interface Iof the insertion tool T is released from the spacer 10, leaving thespacer 10 implanted within the patient.

SUMMARY

An article of manufacture is disclosed in one feature of the presentdisclosure that comprises an intervertebral spacer that includes a mainbody having a distal end and a proximal end that are connected by sidewalls that are spaced apart from one another so as to define an interiorcavity therebetween, the proximal end having a first proximal end walland a second proximal end wall, a proximal end opening being definedbetween the first proximal end wall and the second proximal end wall;and an articulating component pivotally mounted within the proximal endopening and configured to interconnect with a tool for inserting theintervertebral spacer. The article of manufacture further comprises aplurality of support structures connected to the intervertebral spacerincluding at least one first support structure configured to support themain body of the intervertebral spacer during manufacture and at leastone second support structure configured to support the articulatingcomponent of the intervertebral spacer during manufacture, the pluralityof support structures being removable from the intervertebral spacerafter manufacture.

An intervertebral spacer is disclosed in one feature of the presentdisclosure that comprises a main body having a distal end and a proximalend that are connected by side walls that are spaced apart from oneanother so as to define an interior cavity therebetween, the proximalend having a first proximal end wall and a second proximal end wall, aproximal end opening being defined between the first proximal end walland the second proximal end wall. The intervertebral spacer furthercomprises an articulating component having an elongated shape with afirst end that is pivotally mounted within the proximal end opening anda second end that is configured to interconnect with a tool forinserting the intervertebral spacer. One of (i) an interior of theproximal end opening and (ii) the first end of the articulatingcomponent includes a protrusion coinciding with a pivotal axis of thearticulating component and another one of (i) the interior of theproximal end opening and (ii) the first end of the articulatingcomponent includes a recess coinciding with the pivotal axis of thearticulating component. The protrusion is configured to be receivedwithin the recess to enable a pivoting motion of the articulatingcomponent about the pivotal axis.

A method for manufacturing intervertebral spacer is disclosed in onefeature of the present disclosure that comprises manufacturing, using anadditive manufacturing processing, atop a surface, at least one firstsupport structure configured to support a main body of theintervertebral spacer during manufacture and at least one second supportstructure configured to support an articulating component of anintervertebral spacer during manufacture. The method further comprisesmanufacturing, using the additive manufacturing processing, the mainbody atop the at least one first support structure, the main body havinga distal end and a proximal end that are connected by side walls thatare spaced apart from one another so as to define an interior cavitytherebetween, the proximal end having a first proximal end wall and asecond proximal end wall, a proximal end opening being defined betweenthe first proximal end wall and the second proximal end wall. The methodfurther comprises manufacturing, using the additive manufacturingprocessing, the articulating component atop the at least one secondsupport structure without any material interconnecting the main body andthe articulating component, the articulating component being pivotallymounted within the proximal end opening and configured to interconnectwith a tool for inserting the intervertebral spacer. The method furthercomprises removing, after the manufacture of the main body and thearticulating component, the at least one first support structure fromthe main body and the at least one second support structure from thearticulating component.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other features of the arrangement,intervertebral spacer, and method are explained in the followingdescription, taken in connection with the accompanying drawings.

FIGS. 1A-1D depict of an intervertebral spacer being introduced into anintervertebral space using a transforaminal approach.

FIGS. 2A-2C are perspective views of an intervertebral spacer adaptedfor introduction using the transforaminal approach.

FIGS. 3A-3C are perspective views of the intervertebral spacer havingremovable supports adapted for additive manufacture of theintervertebral spacer.

FIGS. 4A-4D are perspective views of the intervertebral spacer of FIGS.3A-3C illustrating removal of the supports after manufacture.

FIGS. 5A-5D are side views and cross-sectional views the intervertebralspacer of FIGS. 3A-3C.

FIGS. 6A-6C are detailed views of the cross-sectional views of theintervertebral spacer of FIGS. 5B and 5D.

FIGS. 7A-7D are side views and cross-sectional views of a main body andan articulating component of the intervertebral spacer of FIGS. 3A-3C.

FIGS. 8A-8C are perspective views of an alternative intervertebralspacer having removable supports adapted for additive manufacture of theintervertebral spacer.

FIGS. 9A-9D are perspective views of the intervertebral spacer of FIGS.8A-8C illustrating removal of the supports after manufacture.

FIGS. 10A-10D are side views and cross-sectional views theintervertebral spacer of FIGS. 8A-8C.

FIGS. 11A-11C are detailed views of the cross-sectional views of theintervertebral spacer of FIGS. 10B and 10D.

FIGS. 12A-12D are side views and cross-sectional views of a main bodyand an articulating component of the intervertebral spacer of FIGS.8A-8C.

FIG. 13 is a logical flow diagram for a method of manufacturing anintervertebral spacer using a three-dimensional object printer orequivalent additive manufacturing process.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of thedisclosure, reference will now be made to the embodiments illustrated inthe drawings and described in the following written specification. It isunderstood that no limitation to the scope of the disclosure is therebyintended. It is further understood that the present disclosure includesany alterations and modifications to the illustrated embodiments andincludes further applications of the principles of the disclosure aswould normally occur to one skilled in the art which this disclosurepertains.

FIGS. 2A-2C are perspective views of an intervertebral spacer 20according to the disclosure which is adapted for introduction using thetransforaminal approach, for example as depicted in FIGS. 1A-1D. Thespacer 20 is comprised of a main body 21 and an articulating component22 (which may also be referred to as an “articulating pin”) that ispivotally mounted within an opening 23 defined in one end of the mainbody 21. As will be described in further detail herein, in at least someembodiments the spacer 20 is formed using a digital additivemanufacturing process, such as three-dimensional object printing (alsoreferred to as simply “3D printing”). Moreover, the spacer 20 isadvantageously designed to be manufactured without the use of anyfrangible support material between the main body 21 and the articulatingcomponent 22, as is required with other designs using a digital additivemanufacturing process.

The main body 21 has a hollow cage structure and is formed primarily byupper and lower walls 24 and by opposite side walls 25, which togetherdefine an interior cavity 26 of the main body 21. The upper and lowerwalls 24 are generally planar and shaped to exhibit a large curvaturethat corresponds to prepared endplates of adjacent vertebrae beingtreated with the spacer 20. The opposite side walls 25 are spaced fromone another and connected to edges of the upper and lower walls 24 so asto define an interior cavity 26 between the opposite side walls 25 andthe upper and lower walls 24. Thus, it should be appreciated that theopposite side walls 25 have a non-planar curved shape configured tomatch the contour of the edges of the upper and lower walls 24, whichmay, for example, emulate the curvature of the epiphyseal ring tofacilitate advancement of the spacer 20 into the intervertebral space.Moreover, it should be appreciated that the upper and lower walls 24 aredefined in part by the upper and lower edges of the opposite side walls25. Likewise, the opposite side walls 25 are defined in part by theedges of the upper and lower walls 24.

At least some of the upper and lower walls 24 and the opposite sidewalls 25 are configured to define large openings 27 that make theinterior cavity 26 accessible from an exterior of the spacer 20. In theillustrated embodiment, only the upper and lower walls 24 define largethrough openings 27. However, in alternative embodiments, only theopposite side walls 25 define large through openings 27 or all four ofthe upper and lower walls 24 and the opposite side walls 25 define largethrough openings 27. In this way, the interior cavity 26 of the mainbody 21 is configured to receive bone growth material, such asmorcellized bone, bone morphogenic protein (BMP), or other compositionsknown to promote bone growth and integration into the adjacent vertebralbodies.

In embodiments in which one or more of the side walls 25 or the upperand lower walls 24 do not define large openings 27, some of the sidewalls 25 or the upper and lower walls 24 may instead be provided with aplurality of smaller openings or apertures 28 passing through thestructure of the respective wall and in communication with the interiorcavity 26. Particularly, in the illustrated embodiment, the upper andlower walls 24 define large through openings 27, whereas the side walls25 define pluralities of smaller openings 28. In alternativeembodiments, the upper and lower walls 24 define pluralities of smalleropenings 28, whereas the side walls 25 define large through openings 27.The smaller openings 28 can have a variety of shapes, including circularor hexagonal, and may extend continuously through the respective sidewall 25 or respective upper or lower wall 24. In one embodiment, therespective side wall 25 or respective upper or lower wall 24 can beconfigured so that the smaller openings 28 define a honeycomb pattern.In some embodiments, the smaller openings 28 are defined by athree-dimensional lattice or mesh structure 30 that forms at least partof the respective side wall 25 or respective upper or lower wall 24. Thesmaller openings 28 and/or the three-dimensional lattice/mesh structures30 are configured to accept bone growth stimulating compositions therethrough to permit bone growth through the respective side wall 25 orrespective upper or lower wall 24.

In some embodiments, the upper and lower walls 24 are provided withsurface features 29 that are configured to engage the prepared surfacesof the adjacent vertebral bodies. Particularly, in one exemplaryembodiment, the surface features 29 are in the form of pyramidalprotrusions or teeth that are adapted to penetrate or otherwise engagewith the prepared endplates of the adjacent vertebrae being treated withthe space 20.

The main body 21 further includes a distal end portion 31 having ablunt-tipped shape, a bullet shape, or other shape configured tofacilitate introduction of the spacer 20 into the intervertebral space.In some embodiments, the distal end portion 31 is formed as a joining orconnection of the distal ends of each of the upper and lower walls 24and the opposite side walls 25 to form a blunt tipped pyramidal shape.In some embodiments, the distal end portion 31 has an at least partiallyhollow structure. In some embodiments, the hollow structure of thedistal end portion 31 may be partially or completely filled with athree-dimensional lattice or mesh structure 30, similar to that whichdefines the smaller openings 28 of side walls 25 or the upper and lowerwalls 24.

In some embodiments, the distal end portion 31 may incorporate thesurface features 29 on one or more of its outer surfaces to furtherenhance the grip between the spacer 20 and the vertebral bodies.Likewise, in some embodiments, the distal end portion 31 may incorporatethe smaller openings 28 to facilitate further bone growth.

The main body 21 further comprises a proximal end portion 32 that isadapted to be engaged by an insertion tool T to perform the TLIF implantprocedure described above. In particular, the proximal end portion 32includes upper and lower walls 33 and an inner wall 34 that define theopening 23 within which the articulating component 22 is mounted. Theupper and lower walls 33 form the proximal end portion of the upper andlower walls 24. In one embodiment, the upper and lower walls 33 includesmall openings 35, which are similar to the smaller openings 28. Theinner wall 34 is connected between inner edges of each of the upper andlower walls 33 so as to provide a structural separation between theopening 23 and the interior cavity 26 of main body 21. The upper andlower walls 33 further include a central boss 36 that amounts to anindentation in the thickness of the upper and lower walls 33, as bestshown in FIG. 2C. The central bosses or indentations 36 serve as a pivotmount for the articulating component 22 mounted within the opening 23between the upper and lower walls 33.

The articulating component 22 has an elongated shape that defines acentral bore 37 that can incorporate threads 38 for engaging theinterface component I of the insertion tool T described above. Thearticulating component 22 is thus generally cylindrical in shape so thatit can pivot freely within the opening 23 of the main body 21. Thecylindrical body of the articulating component 22 includes an enlargedend having protrusions 39 that are configured to be seated within theindentations 36 defined in the upper and lower walls 33 of the proximalend portion 32. The distal end of the cylindrical body of thearticulating component 22 is configured to receive the interfacecomponent I of the insertion tool T. In one embodiment, the enlarged endof the articulating component 22 terminates in a truncated nose 40 witha central bore 41 extending from the threaded bore 37.

It should be appreciated that the interface between the indentations 36and the protrusions 39 of the articulating component 22 operates as apivot axis for pivoting of the component form side-to-side between theupper and lower walls 33 of the proximal end portion 32. Thisarticulating movement allows the spacer 20 to be manipulated asnecessary for introduction using the transforaminal approach. In oneaspect, the articulating component 22 includes flattened sides 42, asshown in FIG. 2B rather than a fully cylindrical body, to reduce thevertical profile of the articulating component 22 while retainingsufficient material to define the threaded bore 37.

In order for the articulating component to be free to pivot within theproximal end portion 30, clearance between the articulating component 22and the main body 21 of the spacer 20 is necessary. Thus, in accordancewith one aspect of the present disclosure, the complete insert 20 ismanufactured using an additive manufacturing process, such as a 3Dprinting, with a uniform gap defined between the articulating component22 and the body 21. However, in a conventional additive manufacturingprocess in which the spacer 20 is formed on its side as illustrated, afrangible support structure needs to be provided between the twocomponents. Particularly, for explanatory purposes only, a conventionaladditive manufacturing process might form the spacer on its side andutilize a frangible bridge to support the articulating component 22during the additive manufacturing process. The frangible bridge would,for example, comprise a thin strip of material between an exteriorsurface of the articulating component 22 and the interior surface of theopening 23 in the main body 21. After manufacture, this thin strip ofmaterial would be broken by forced movement of the articulatingcomponent 22 relative to the main body 21, or be otherwise removed fromthe spacer 20. However, this technique has the disadvantage of leavingsmall material remnants of frangible bridge situated between thearticulating component 22 and the main body 21 that may inhibit smoothpivotal movement of the articulating component 22 with respect to themain body 21.

With reference to FIGS. 3A-3C, the intervertebral spacer 20 of thepresent disclosure is advantageously designed to be manufactured withoutthe use of any frangible support material between the main body 21 andthe articulating component 22, as is required in a conventional additivemanufacturing process. Instead, the spacer 20 is produced in an additivemanufacturing process in which the main body 21 and the articulatingcomponent 22 are separately supported during manufacture. Particularly,as shown in FIG. 3A, the spacer 20 further includes support structures50 and 51 that extend from the main body 21 and the articulatingcomponent 22, respectively. The support structures 50 and 51 areadvantageously separate from one another and no frangible supportmaterial is used that interconnects the main body 21 with thearticulating component 22. It should be appreciated that the supportstructures 50 and 51 may a wide variety of forms include any number ofindividual elements. For example, in one embodiment, the supportstructures 50 include four leg structures rather than two wallstructures. Similarly, in one embodiment, the support structure 51includes two flat wall structures, rather than a rounded wall structure.

FIG. 3B illustrates the main body 21 without the articulating component22 mounted therein. As can be seen, support walls 50 extend proximallyfrom the proximal end portion 32 of the main body 21 and are generallyplanar and contiguous with the upper and lower walls 33 of the proximalend portion 32. Likewise, FIG. 3C illustrates the articulating component22 separated from the main body 21. As can be seen, a support 51 extendsproximally from the end of the threaded bore 37 and generally followsthe cylindrical or flattened cylindrical contour of the articulatingcomponent 22. FIGS. 4A-4B are additional perspective views of theintervertebral spacer 20 support structures 50 and 51, showing therelative orientations of the support structures.

The support structures 50 and 51 are configured to support the spacer 20when it rests on a horizontal surface in a vertical orientation. To thisend, the support structures 50 and 51 have flat ends 52 and 53,respectively, best seen in FIG. 4B, which are opposite the ends thatconnect to the main body 21 or articulating component 22, respectively,and are configured to facilitate stable resting of the spacer 20 on thehorizontal surface in the vertical orientation. As used herein, the term“vertical orientation” used with respect to the intervertebral spacer 20refers to an orientation in which the opening 23 of proximal end portion32 of the main body 21 faces in the direction of gravity and/or facesthe horizontal surface, such that supports 50 and 51, extending from theproximal end portion 32 of the main body 21 and from the articulatingcomponent 22 may simultaneously rest on the horizontal surface.

The supports 50 and 51 enable the main body 21 and the articulatingcomponent 22 to be manufactured together in the vertical orientationusing a digital additive manufacturing process, such as 3D printing,without the need for any frangible support material that interconnectsthe main body 21 with the articulating component 22. In particular, inthe vertical orientation, the main body 21 and the articulatingcomponent 22 can be printed simultaneously with the articulatingcomponent 22 already positioned within the opening 23 of the main body21, but without contact or connection between the main body 21 and thearticulating component 22. It can be appreciated that processes such as3D printing can very accurately lay down layers of material withaccurately sized vertically oriented gaps between the material so thatthe protrusions 39 of the articulating component 22 can be very near,but not touching, the indentations 36 in the main body 21. In this way,the articulating component 22 reliably provides a smooth pivot motionthat is free from undesirable material remnants of a frangible bridge.After manufacture, the supports 50 and 51 are removed, as shown in FIGS.4C-4D.

FIGS. 5A-5D are side views and cross-sectional views of theintervertebral spacer 20. Particularly, FIG. 5A is a side view of theintervertebral spacer 20 and identifies a vertical cross-section A-Awhich cuts through the intervertebral spacer 20 in a manner that isparallel with and coincides with a pivotal axis P of the articulatingcomponent 22. FIG. 5B is a cross-sectional view of the verticalcross-section A-A of the intervertebral spacer 20. As can be seen, theprotrusions 39 of the articulating component 22 take the form oftruncated cones which extend from the body of the articulating component22 in the direction of and coinciding with the pivotal axis P. Inalternative embodiments, the protrusions 39 take the form of bluntedcones. Likewise, the indentations 36 in the proximal end portion 32 ofthe main body 21 are in the form of truncated conical recesses in thedirection of and coinciding with the pivotal axis P. In alternativeembodiments, the indentations 36 take the form of blunted conicalrecesses. As can be seen in the detail view of FIG. 6B, the truncatedconical shape of the protrusions 39 of the articulating component 22thus have a shape that closely coincides with the indentations 36 in theproximal end portion 32 of the main body 21. However, as best seen inthe detail view of FIG. 6C, a small gap 42 is maintained between theupper/lower wall 33 and the articulating component 22. In this way, thearticulating component 22 is held firmly in place in all directionswithin the opening 23 of the main body 21 with minimal movement of thearticulating component 22 being possible, aside from the singularrotational degree of freedom about the pivotal axis P.

Similarly, FIG. 5C is a side view of the intervertebral spacer 20 andidentifies a vertical cross-section C-C which cuts through theintervertebral spacer 20 in a manner that is perpendicular with apivotal axis P of the articulating component 22. FIG. 5D is across-sectional view of the vertical cross-section C-C of theintervertebral spacer 20. As can be seen, the inner wall 34 and the sidewalls 25 are shaped to accommodate rotation of the articulatingcomponent 22 about the pivotal axis P within the opening 23.Additionally, the inner wall 34 and the side walls 25 are shaped tolimit the range of motion of the articulating component 22 within theopening 23. In the illustrated example the inner wall 34 and the sidewalls 25 limit the range of motion of the articulating component 22 toabout 55° of possible rotation about the pivotal axis P before beinginhibited from further rotation. As best seen in the detail view of FIG.6A, in order to delimit the range of motion of the articulatingcomponent 22, the inner wall 34 includes a limiting wall portions 43 and44 that each have a surface facing the interior of the opening 23 thatdelimits the range of motion of the articulating component 22 byinhibiting its rotation about the pivotal axis P. The limiting wallportions 43 and 44 are joined together at an angle (about 90°, in theillustrated embodiment), which in part defines the total range of motionof the articulating component 22.

In some embodiments, such as the one illustrated, the inner wall 34and/or the side walls 25 are configured to accommodate a greater amountof rotation in one direction than the other, relative to the verticalorientation of articulating component 22 in which the articulatingcomponent 22 is originally manufactured (i.e., the illustratedorientation of the articulating component 22). In one embodiment, thearticulating component 22 can rotate further in a direction of thecurvature of the main body 21 (to the left in the illustration of FIG.6A). In the illustrated embodiment, starting from the verticalorientation of articulating component 22, the articulating component 22can rotate about 45° in the direction of the curvature of the main body21 (clockwise rotation, in the illustrated perspective) and about 10° inthe opposite direction (counter-clockwise rotation). To this end,limiting wall portion 44, is has a flared end portion 45 (which isopposite the end that joins with the limiting wall portion 43) thatfurther inhibits rotation of the articulating component 22 about thepivotal axis P in that direction (to the right in the illustration ofFIG. 6A). Alternatively, the limiting wall portion 44 could similar havea bent end portion 45, to achieve the same result.

Finally, as can be seen in the FIGS. 5B and 5D, the longitudinal axis ofthe threaded bore 37 is perpendicular to a pivotal axis P of thearticulating component 22. In this way, the singular rotational degreeof freedom about the pivotal axis P enables adjustment of the interfaceangle between the main body 21 of the intervertebral spacer 20 and theinsertion tool T. As discussed above with respect to FIGS. 1A-1D, thisadjustment is useful to facilitate a transforaminal approach forimplanting an intervertebral spacer, such as the intervertebral spacer20.

FIGS. 7A-7D are side views and cross-sectional views of the main body 21and articulating component 22 of the intervertebral spacer 20.Particularly, FIG. 7A is a side view of the main body 21 and identifiesa vertical cross-section G-G which cuts through the intervertebralspacer 20 in a manner that is parallel with and coincides with thepivotal axis P of the articulating component 22. FIG. 7B is across-sectional view of the vertical cross-section G-G of theintervertebral spacer 20. As mentioned above, in the exemplaryillustrated embodiments, the indentations 36 in the proximal end portion32 of the main body 21 are in the form of truncated conical recesses inthe direction of and coinciding with the pivotal axis P. As can be seen,the conical shape of the indentations 36 extend into the upper and lowerwalls 33 at an angle of about 45°, relative to the interior surface ofthe upper and lower walls 33. The conical shape is truncated at abouttwo-thirds of the thickness of the upper and lower walls 33.

Similarly, FIG. 7C is a side view of the articulating component 22 andidentifies a vertical cross-section F-F which cuts through thearticulating component 22 in a manner that is parallel with andcoincides with the pivotal axis P of the articulating component 22. FIG.7D is a cross-sectional view of the vertical cross-section F-F of theintervertebral spacer 20. As mentioned above, the protrusions 39 of thearticulating component 22 take to form of truncated cones which extendfrom the body of the articulating component 22 in the direction of andcoinciding with the pivotal axis P. As can be seen, the conical shape ofthe protrusions 39 extend from the body of the articulating component 22at an angle of about 45°, relative to the exterior surface of thearticulating component 22. The conical shape of the protrusions 39 istruncated so as to match the truncated conical shape of the indentations36 in the proximal end portion 32 of the main body 21.

As best seen in FIG. 7C, the truncated nose 40 has a roundedsemi-circular form in a direction that is perpendicular to the pivotalaxis P. However, as best seen in FIG. 7D, the truncated nose 40 has atruncated triangular form in a direction parallel with the pivotal axisP, having an angle of about 45°. Additionally, as can be seen in FIG.7D, the central bore 41 extends from the threaded bore 37 through thetip of the truncated nose 40 so as to communicate the threaded bore 37with the opening 23. Finally, a distal end of articulating component hasa beveled edge 46. The surface of the beveled edge 46 has a normalvector at an angle of about 46.5°, relative to a normal vector to therest of the exterior surface of the articulating component 22.

FIGS. 8-12 illustrate an intervertebral spacer 20′, which is similar tothe intervertebral spacer 20 except in the manner of engagement betweenthe main body 21 and the articulating component 22 to provide rotationabout the pivotal axis P. FIGS. 8-12 are essentially similar to FIGS.3-7 and are not described in complete detail. In particular, FIGS. 3A-3Care essentially similar the FIGS. 8A-8C, FIGS. 4A-4D are essentiallysimilar to FIGS. 9D-9D, FIGS. 5A-5D are essentially similar to FIGS.10D-10D, FIGS. 6A-6D are essentially similar to FIGS. 11D-11D, and FIGS.7A-7D are essentially similar to FIGS. 12D-12D. Moreover, likecomponents are labeled with like reference numerals in the FIGS. 8-12.

With reference to FIG. 10B, unlike the intervertebral spacer 20, theproximal end portion 32 of the intervertebral spacer 20′ has protrusions36′ that take the form of cones which extend from the interior surfaceof the upper and lower walls 33 in the direction of and coinciding withthe pivotal axis P. Similarly, the articulating component 22 hasindentations 39′ that are in the form of conical recesses in thedirection of and coinciding with the pivotal axis P. As can be seen inthe detail view of FIG. 11B, the conical shape of the protrusions 36′ inthe proximal end portion 32 of the main body 21 have a shape thatclosely engages with the indentations 39′ of the articulating component22. However, as best seen in the detail view of FIG. 11C, a small gap 42is maintained between the upper/lower wall 33 and the articulatingcomponent 22. In this way, the articulating component 22 is held firmlyin place within the opening 23 of the main body 21 with minimal movementof the articulating component 22 being possible, aside from the singularrotational degree of freedom about the pivotal axis P.

As best seen in FIG. 12B, the conical shape of each of the protrusions36′ extends from the interior surface of the upper and lower walls 33 atan angle of about 45°, relative to the interior surface of the upper andlower walls 33, and terminates at a point having a 90° angle. Likewise,as best seen in FIG. 12D, the conical shape of the indentations 39′extend into articulating component 22 at an angle of about 45°, relativeto the exterior surface of the articulating component 22, and terminatesat a point having a 90° angle.

As best seen in FIG. 12C, the articulating component 22 theintervertebral spacer 20′ has truncated nose 40′ having a rounded formin a direction that is perpendicular to the pivotal axis P. However, asbest seen in FIG. 12D the truncated nose 40′ has a squared form in adirection parallel with the pivotal axis P. Additionally, as can be seenin FIG. 12D, the central bore 41′ extends from the threaded bore 37, butis terminated in a conical point and does not extend completely throughthe truncated nose 40′.

In at least one embodiment, the spacer 20, 20′ is manufactured using adigital additive manufacturing process and, in particular, using athree-dimensional object printer. It will be appreciated that digitaladditive manufacturing is a process of making a three-dimensional solidobject of virtually any shape from a digital model by adding material.Three-dimensional object printing or “3D printing” is an additiveprocess in which one or more ejector heads deposit material toincrementally build an object. Material is typically deposited indiscrete quantities in a controlled manner to form layers thatcollectively form the object. The initial layer of material is depositedonto a substrate, and subsequent layers are deposited on top of previouslayers. Three-dimensional object printing is distinguishable fromtraditional object-forming techniques, which mostly rely on the removalof material from a work piece by a subtractive process, such as cuttingor drilling.

FIG. 13 is a logical flow diagram for a method 100 of manufacturing theintervertebral spacer 20, 20′ using a three-dimensional object printeror equivalent additive manufacturing process. It will be appreciated bythose of ordinary skill in the art that a three-dimensional objectprinter may, for example, comprise a platen, an ejector head, and acontroller. The ejector head has one or more ejectors configured toeject drops of build material towards a surface of the platen to form athree-dimensional object. The ejector head is configured to moverelative to the platen. Particularly, either the platen is moved viaoperation of actuators operatively connected to the platen or theejector head is moved via operation of actuators operatively connectedto the ejector heads, or both. The controller is operatively connectedto the ejector head and the actuators and configured to operate theejector head and the actuators with reference to image data, such as a3D model, to form a three-dimensional object on the surface of theplaten.

The method 100 begins with a step of operating a three-dimensionalobject printer to manufacture independent support structures configuredto separately support a main body and an articulating component of anintervertebral spacer during manufacture (block 110). Particularly, acontroller operates actuators to position ejectors of an ejector headabove a platen and to eject build material onto the platen at differentlocations to form the support structures 50 and 51. Generally, thesupport structures 50 and 51 are built by forming one layer of buildmaterial after another in a sequential manner, where each layer is builtatop the preceding layer. To form each layer of the support structures50 and 51, the controller may, for example, operate the actuators of theprinter to sweep the ejector head one or more times relative to theplaten in a process direction, which is parallel to the platen, whileejecting drops of material onto the platen. After each layer is formed,the ejector head moves away from the platen in a vertical direction,which is perpendicular to the platen, to begin printing the next layeratop the previously formed layer.

The method 100 continues with a step of operating the three-dimensionalobject printer to manufacture the intervertebral spacer having the mainbody and the articulating component pivotally mounted within an openingof the main body, the main body and the articulating component beingmanufactured atop the independent support structures and without anymaterial interconnecting the main body and the articulating component(block 120). Particularly, a controller operates actuators to positionejectors of an ejector head above a platen and to eject build materialonto the platen at different locations to form the main body 21 of theintervertebral spacer 20 atop the support structures 50 and thearticulating component 22 of the intervertebral spacer 20 atop thesupport structure 51. As with the support structures 50 and 51, the mainbody 21 and the articulating component 22 are built by forming one layerof build material after another in a sequential manner, where each layeris built atop the preceding layer.

As the main body 21 and the articulating component 22 are formed, theyare independently supported by the supports 50 and 51. In particular,the proximal end 32 of the main body 21 is formed directly atop thesupports 50 and the distal end of the articulating component 22 isformed directly atop the support 51. This is made possible by virtue ofthe vertical orientation of the intervertebral spacer 20, 20′ duringmanufacture. Particularly, the upper and lower walls 34 of the proximalend 32 rest directly atop the two supports 50 with an orientation suchthat the opening 23 faces the support 51 (which is situated between thetwo supports 50). This enables the articulating component 22 to beformed within the opening 23 simultaneously with the formation of theproximal end 32 of the main body 21. Thus, the main body 21 and thearticulating component 22 can be built with the small gap 42 situatedtherebetween, as described above with respect to FIGS. 6B-6C or FIGS.11B-11C. Moreover, there is advantageously no need for any frangiblesupport material between the articulating component 22 and the main body21 to hold the articulating component 22 within the opening 23 duringmanufacture.

The method 100 concludes with removing, after manufacture of theintervertebral spacer, the support structures from the main body and thearticulating component of the intervertebral spacer (block 130).Particularly, after the additive manufacturing process is complete, thesupports 50 and 51 are removed, leaving the finished intervertebralspacer 20, as shown in FIGS. 4C-4D or FIGS. 9C-9D. The supports 50 and51 can be configured to be frangible so as to be easily snapped off fromthe articulating component 22 and the main body 21. In that regard, aline of weakness or thinner material can be formed between the supportand the component being supported so that the supports can still providevertical support for the component during manufacture, but can bereadily snapped off by a lateral force. Alternatively, the buildsupports can be removed in a machining operation, such as cutting. Itcan be appreciated that the supports can be removed at any time aftermanufacture and before the intervertebral spacer 20, 20′ is introducedinto a patient.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, the same should be considered asillustrative and not restrictive in character. It is understood thatonly the preferred embodiments have been presented and that all changes,modifications and further applications that come within the spirit ofthe disclosure are desired to be protected.

What is claimed is:
 1. A method of manufacturing an intervertebralspacer, the method comprising: manufacturing, using an additivemanufacturing process, atop a surface, at least one first supportstructure configured to support a main body of the intervertebral spacerduring manufacture and at least one second support structure configuredto support an articulating component of an intervertebral spacer duringmanufacture; manufacturing, using the additive manufacturing process,the main body atop the at least one first support structure, the mainbody having a distal end and a proximal end that are connected by sidewalls that are spaced apart from one another so as to define an interiorcavity therebetween, the proximal end having a first proximal end walland a second proximal end wall, a proximal end opening being definedbetween the first proximal end wall and the second proximal end wall;manufacturing, using the additive manufacturing process, thearticulating component atop the at least one second support structurewithout any material interconnecting the main body and the articulatingcomponent, the articulating component being pivotally mounted within theproximal end opening and configured to interconnect with a tool forinserting the intervertebral spacer; and removing, after the manufactureof the main body and the articulating component, the at least one firstsupport structure from the main body and the at least one second supportstructure from the articulating component.
 2. The method according toclaim 1, the manufacturing of the main body further comprising:manufacturing the proximal end of the main body directly atop the atleast one first support structure.
 3. The method according to claim 2,the manufacturing of the main body further comprising: manufacturing thefirst proximal end wall directly atop a first portion of the at leastone first support structure; and manufacturing the second proximal endwall directly atop a second portion of the at least one first supportstructure.
 4. The method according to claim 3, the manufacturing of theat least one second support structure further comprising: manufacturingthe at least one second support structure situated between the firstportion of the at least one first support structure and the secondportion of the at least one first support structure.
 5. The methodaccording to claim 2, the manufacturing of the main body furthercomprising: manufacturing the proximal end of the main body directlyatop the at least one first support structure oriented such that theproximal end opening of the proximal end faces the at least one secondsupport structure.
 6. The method according to claim 2, the manufacturingof the articulating component further comprising: manufacturing thearticulating component within the proximal end opening simultaneouslywith the manufacturing of the proximal end of the main body.
 7. Themethod according to claim 1, the manufacturing of the articulatingcomponent further comprising: manufacturing the articulating componentwithin the proximal end opening with a gap defined between thearticulating component and the proximal end of the main body.
 8. Themethod according to claim 1, the manufacturing of the articulatingcomponent further comprising: manufacturing a distal end of thearticulating component directly atop the at least one second supportstructure.
 9. The method according to claim 8, the manufacturing of thearticulating component further comprising: manufacturing thearticulating component directly atop the at least one second supportstructure oriented such that a central bore in the distal end of thearticulating component faces in a direction of the at least one secondsupport structure, the central bore being configured to interconnectwith the tool.
 10. The method according claim 1, the removing furthercomprising: applying lateral forces to break the at least one firstsupport structure from the main body; and applying lateral forces tobreak the at least one second support structure from the articulatingcomponent.
 11. The method according claim 1, the removing furthercomprising: cutting, with a machine, the at least one first supportstructure from the main body; and cutting, with the machine, the atleast one second support structure from the articulating component. 12.The method according claim 1, the additive manufacturing processcomprising: operating a three-dimensional object printer to eject buildmaterial toward the surface.
 13. The method according to claim 12, theoperating the three-dimensional object printer further comprising:ejecting the build material to form layers of build material, one afteranother in a sequential manner.